Lip serums can indeed help with pigmentation, but it largely depends on the specific ingredients they contain. Pigmentation on the lips can be caused by a variety of factors such as sun exposure, smoking, hormonal changes, or even certain medications.

To address pigmentation, look for lip serums that contain ingredients known for their brightening and lightening properties. These may include:

1. Vitamin C: This potent antioxidant is known for its ability to brighten skin and reduce the appearance of pigmentation. It works by inhibiting the enzyme tyrosinase, which is responsible for the production of melanin, the pigment that gives skin its color.

2. Niacinamide: Also known as vitamin B3, niacinamide is another ingredient that can help reduce pigmentation. It works by slowing down the transfer of melanin to your skin's surface.

3. Licorice Root Extract: This natural ingredient has been shown to lighten skin and reduce the appearance of dark spots and discoloration.

4. Alpha Arbutin: This is a derivative of hydroquinone and has been proven to inhibit melanin production.

Remember, it's important to also protect your lips from the sun as UV rays can exacerbate pigmentation. Look for lip products with SPF and try to limit your sun exposure when possible.

As with any skincare product, results can vary from person to person. It may take several weeks of consistent use to see noticeable improvements in pigmentation. If you're dealing with persistent or severe lip pigmentation, it may be worth consulting with a dermatologist.